Assume That Human Recorded History Can Be Stretched Back to 4600

Q42: Which organisms were benthic (bottom dwellers) and

Q43: Consider the names of the eras in

Q44: Which two Paleozoic, geologic, time-scale periods used

Q45: An unconformity is a buried _.<br>A) surface

Q46: In radiometric dating, an unstable radioactive isotope

Q48: Which of the following is the name

Q49: The name of which geologic era means

Q50: The radioactive isotopes uranium- 238, uranium- 235,

Q51: Which of the following is not a

Q52: Of an original amount of radioactive parent